diff --git a/SAS/TMSS/backend/src/tmss/tmssapp/models/specification.py b/SAS/TMSS/backend/src/tmss/tmssapp/models/specification.py
index d7638ff2b0fa7a4ed2837d74e9315638b57f5418..8d64f0aeaf70bdaedb782374718668efae7a642a 100644
--- a/SAS/TMSS/backend/src/tmss/tmssapp/models/specification.py
+++ b/SAS/TMSS/backend/src/tmss/tmssapp/models/specification.py
@@ -421,9 +421,9 @@ class SchedulingUnitDraft(NamedCommon, TemplateSchemaMixin):
             self.ingest_permission_required=True
 
         # Propagate project piggyback values as default for scheduling_unit_draft
-        if self.piggyback_allowed_tbb is None and hasattr(self, 'scheduling_set'):
+        if self._state.adding and self.piggyback_allowed_tbb is None and hasattr(self, 'scheduling_set'):
             self.piggyback_allowed_tbb = self.scheduling_set.project.piggyback_allowed_tbb
-        if self.piggyback_allowed_aartfaac is None and hasattr(self, 'scheduling_set'):
+        if self._state.adding and self.piggyback_allowed_aartfaac is None and hasattr(self, 'scheduling_set'):
             self.piggyback_allowed_aartfaac = self.scheduling_set.project.piggyback_allowed_aartfaac
     
         self.annotate_validate_add_defaults_to_doc_using_template('requirements_doc', 'requirements_template')
@@ -498,9 +498,9 @@ class SchedulingUnitBlueprint(RefreshFromDbInvalidatesCachedPropertiesMixin, Tem
             self.ingest_permission_required = self.draft.ingest_permission_required
 
         # Propagate scheduling_unit_draft piggyback values as default for scheduling_unit_blueprint
-        if self.piggyback_allowed_tbb is None and hasattr(self, 'draft'):
+        if self._state.adding and self.piggyback_allowed_tbb is None and hasattr(self, 'draft'):
             self.piggyback_allowed_tbb = self.draft.piggyback_allowed_tbb
-        if self.piggyback_allowed_aartfaac is None and hasattr(self, 'draft'):
+        if self._state.adding and self.piggyback_allowed_aartfaac is None and hasattr(self, 'draft'):
             self.piggyback_allowed_aartfaac = self.draft.piggyback_allowed_aartfaac
 
         super().save(force_insert, force_update, using, update_fields)